Refrigerator defrosting timer



NOV. 1l, 1952 D, MORRlsON 2,617,900

REFRIGERATOR DEFROSTING TIMER Filed March 29, 1950 2 Sl-IEETS--Sl-{EET l2gjj Z8 d f l 1" l Y, M

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D. MORRISON REFRIGERATOR DEFROSTING TIMER Nov. ll, 1952 2 SHEETS-SHEET 2Filed March 29, 1950 Marr/'son .and speed reducing unit I6.

Patented Nov. 11, 1952 REFRIGERATOR DEFROSTING TIMER David- Morrison,Manitowoc, Wis., assignor to Paragon Electric Company, Two Rivers, Wis.,a corporation of Wisconsin Application March 29, 1950, YSerial No.152,733

7 Claims. (Cl. 200-33) The present invention relates particularly totimers adapted to open and close the electrical circuits forrefrigerators in order to effect automatic defrosting at regularintervals; although the use of the invention is not vlimited to thisfield.

In my prior application, Ser. No. 50,902, filed September 24, 1948, Ihave disclosed a defrosting system of the type just described. Thepresent invention may be said to have for its object to produce a timerwhich is simpler in construction than that disclosed in the aforesaidapplication, and which is reliable, efficient in operation and verydurable. Y e

The various features of novelty whereby the present'invention ischaracterized will hereinafter be pointed out with particularity in theclaims, but, for a full understandingA of the inveritionV and of itsobjects and advantages. reference may be had to the following detaileddescription taken in Vconnection with the accompanying drawings,wherein: ,e y Figure lis a perspective View of a timer embodying thepresent invention, the conventional casing being omitted; Fig. 2 is atop plan view of a part-of the timer, with the combined knob and pointeromitted; Fig. 3 is a side elevational view of the timer as itappearsinand lookingrat it from below Fig; 2; Figs. 4 and 5 are views similar toFigs. 2 and 3, respectively, illustrating the conditions which exist ata different point in a cycle from that corresponding'to Figs. Zand 3;Figsf and 7 are also views similar to Figs. 2 and 3, respectively,illustrating another set of con.- ditions-at` still another point insuch cycle; Fig. 8 is fa section on line 8 8 of Fig. 2; Fig. 9 isaperspective view` of the finger piece `for .adjusting one oi' two camsangularly with respect to the otherj Figs. l and 11 are `two perspectiveviews of the cam to which the :linger piece is connected; and Fig. A12is aperspective View ofthe second of the .two cams andthe shaft withwhich it is interlockedsc' as to be compelled to rotate therewith.

Referring to Fig. l of the drawings, I represents a flat plate on whichthe various parts of the timer'mechanism are mounted. On the under sideof this plate is any suitable electric motor Above the plate is a largegear wheel Il in mesh with a pinion I8 that forms the last element inthe gear train through which the timer mechanism proper is driven. Alittle above, and coaxial with, wheel Il is a somewhat smaller gearwheel I9, and above and near the latter wheel is a third gear Wheel 20,of the same diameter as and coaxial therewith. The number of teeth isnot the same in gear wheels I3 and 20, as there must be at least onemore tooth in one wheel than in the other. In the arrangement shownthere are one hundred and twenty teeth in wheel I9, whereas there areonly one hundredand nineteen teeth in wheel 2B. Gear wheel kI'l has onthe upperside a pin or post 2I lon which is a looser pinion 22 thatmeshes with the teeth on each of the wheels i9 and 20. Above and coaxialwith the gears are two superimposed cams 23 and 24, preferably ofinsulating material, coaxial with the three gear wheels. Above thecamsis a combined pointer and knob 25. Cam 23 has a Wide annular ange 23athat rests on the gear wheel or disc 20.

yPlate I5 has at one end two spaced', upturned parts .15a and I5`b. Aslab 2,6 of insulating material spansthe space between saidV upturnedparts,` and is xed to the latter. Carried-by member 26 is a switchadaptedto be controlled by the cams. The switch is shownV as comprisingtwo spring arms 21 and 28, each anchored atone end to the supportingmember 26 and having portions thereof extending radially 0f the; gearWheels over` ilange 23a. Switch arrn 2l isbent downwardly near its freeend and then horizontally to provide a toepiece 29 that normally liesnear the. flange` on cam 23. Arm 28, the radial portion of whichliesdirectly lover thecorrespondingl part of arm 21, vis a straightpiece. The switch arms are provided with .cooperating contacts 30 and3|, respectively, inwardly .from their free. ends. When the switch isnot under constraint, the contacts on the arms arepressed firmly intoengagement with each other, through the spring action of the arms. Inother words, theswitch is self closing. y u f, The details ofessentialparts that have now been described in general terms, only..Aare .illusitrated in Figs. 8-12. Y i

. As shown in Fig. 8, the large gear wheels are supported by a sturdyvertical column or post 32 fixed to and rising from plate, I5. Thepostis reduced in diameter a short-.distance above. the plate toprovidea` shoulder 33 on which gear wheel Il rests. At a littledistanceaboveshoulder 33 there occurs a second reduction in'diameterv ofthe post to provide a shoulder 34 on which gear wheel IQ rests. A thirdreduction inthe diameter of the post, at a stillhigher level, provides athird annular shoulder 35 on which gear wheel 2 rests. There is a spacer36 aroundthe post, between gear wheels I'l and I9. i

to the post byl pressing it on, or in ,any-other suitable way. l f 1 -YThe body portion of cam23 isan inverted cup the chamber 23b in which issubstantiallylarger' in diameter than the upper end of the post. Gearwheel 20 has on the upper side a-tubular hub 3l that ts around the postand provides along bearing for this wheel. Surrounding' this" hub, andtting it closely, is a torsion spring 38 one end 39., ol' which, isengaged in a groove 23c1 opening out from one side of the chamber in cam23. This arrangement constitutes a clutch that permits the cam and gearwheel 2 to turn freely, relatively to each other, in one direction, andprevent relative movement in the opposite direction. rlhe reason forhaving the clutch is to permit the cam to be turned by hand, relativelyto gear wheel 29, for the purpose of selecting the point in time atwhich the switch shall open. In order that cam 23 may be turned by meansof knob 25, I make `the post tubular in form to serve as a bearing andsupport for loose shaft ii. This shaft contains two circumferentialgrooves iii and #l2 that lie, respectively, immediately below and abovethe post. When fiat C-'shaped keys t3 are entered in these grooves, theshaft is held against lengthwise displacement, while free to rotate.That part -l of the shaft above groove 62 is iiattened so that, when itis slipped through a correspondingly shaped hole in the top wall of thechamber in cam 23 and through a hub 45 projecting up from the cam, theshaft and cam are securely interlocked against turning movementsrelatively to each other.

Shaft 40 extends up well above cam 23, and cam 24. Cam 2li and the shaftare not interlocked against relative angular movements. It will be seenfrom Figs. 10 and l1 that cam 24 has on its upper side a hub 46 in theform of a sleeve slotted from top to bottom at two diametrically opposedpoints. A finger piece 41, best shown in Fig. 9, is slipped on this hub.This linger piece is shown as being in the form of a metal disc i8having a stem le that projects radially therefrom; the outer end of thestem being bent up at rightangles to the rest of the stem. The disccontains a central hole di) to receive the hub on the cam, together withtwo opposed lugs 5|, 5I that extend inwardly from the sides of the hole.These lugs enter the slots in the sleeve hub and interlock the cam andfinger so that they must turn With each other. The shaft is providedwith a groove 52, similar to grooves il and 42, pla-ced a little abovethe lower end of the hub 46. To apply the finger piece in the assembly,the hole in the finger piece is first registered with the upper end ofthe shaft, with the lugs 5| at the fiat sides of the latter. Then, aftercam 2d has been turned with the slots in the hub registering with thelugs on the linger piece, the latter may be moved down over the hubuntil it reaches the level of the groove 52 in the shaft. Thereupon thefinger piece may be turned until the lugs enter this groove and allowthe nnger piece to turn freely on the shaft. By placing the groove alittle above the top of the body portion of the cam member, room isprovided between the finger piece and such body portion for a springwasher 53. In making the assembly, the washer is placed in positionbefore the finger piece is applied, so that the washer mut be stressedsomewhat to allow the finger piece to come down far enough to entergroove52. Thus the cams are yieldingly pressed together, so that theupper cam is frictionally held against turning on the lower cam.

As shown in Fig. l, the combined knob and pointer 25 has in the edge ofits disc-like portion 54 a wide notch 55. The upwardly bent end of thestem member of the nger piece 4l lies in c this notch, so that theangular movement of the finger piece and the upper cam, relative to thelower cam, is limited to the angular width of the notch.

The details of the two cams are best shown in i Figs. 10, 11 and 12.Thus, as shown in Fig. l2, the lower cam has an arcuate ledge, the topof which is a cam track 23C, rising from the level of the top surface ofthe fiange to a high level of any desired angular length. Similarly, cammember 24 has an arcuate ledge of the same radius as the other ledge andprovided with a cam track 24a that is much like the other track. Each ofthe two ledges terminates abruptly at the high end, and the cams are sodisposed, that the high ends of both trail while the timer is operating.The parts are so proportioned that normally the free end of the lowerswitch arm lies below the level of the high portion of the lower camtrack, and the free end of the upper arm of the switch lies below thelevel of the high part of the upper cam track. However, the free end ofthe lower switch arm lies above the level of the low advance end of thelower cam track. A further characteristic of the switch and cams is thatthe switch remains closed while both switch arms are above the highportions of the corresponding cam tracks. The camming ledge on the lowercam member is of greater angular length than :1 the ledge of the lowercam. This allows the low end of the lower track to be in advance of thecorresponding end of the upper track at times when the trailing ends arein the same vertical plane.

Assuming that the timer has been set and that the motor is running,pinion 22 is continuously carried around the stationary gear wheel, andis thus compelled simultaneously to resolve about its own axis. Thepinion also rolls along the toothed edge of of the upper gear wheel;but, be-

` cause of the difference in the number of teeth in the wheels, theloose, upper gear wheel 2!! completes a revolution after the pinion hasengaged only one hundred and nineteen of the teeth in the stationarywheel. Therefore, wheel 2U is positively turned through an angle,corresponding to a single tooth, during each revolution of the pinionaround the stationary gear wheel.

Where the timer is intended to control the defrosting of a refrigeratorthe mechanism may be calibrated to cause gear wheel 20 to revolve oncein twenty four hours.

To determine the point in each twenty four hour cycle at which theswitch opens, the combined knob and pointer 25 is turned to point to thedesired hour and minute on the usual dial, not shown. To determine thelength of time during which the switch remains open, linger piece 67 isshifted to adjust the positions of the cams relative to each other. Whenthe finger piece is at one end of the notch in member 25 the switch willnot open at any time; because the trailing end of the upper cam track isthen directly above or, if desired, ahead of the trailing end of thelower track. When the nger piece leaves that end of the notch the camsare set to effect a switch opening once in each revolution of wheel 20,the length of time during which the switch remains open increasing asthe finger piece is shifted Valong the notch.

rEhe manner in which the cams operate or control the switch is apparentfrom the drawings. Thusin Figs. i, 3 and 5 both switch arms are clear ofthe cam tracks and the switch is closed. In Fig. 5 the lower cam hasflexed both switch rms upwardly, raising the upper arm to such a levelthat the upper cam need not exert any lifting eort; serving merely as asupport for the upper switch arm after the lower arm drops olf the lowercam track at the traling end of the latter. Thus, with the parts in thepositions Shawna, ne, 5, triestina wondere-nain @19ste even, thoughjthelippen Cem' track were.notl D, ent.' onlywhen thelower armriahea'h @r9ping, e,- poini While meppel: tratt still under? lies. theV upper. arm,as iniFig. 7, doesjthe upper ingfa slightly larger number ofteeth. thanthe` other, means for mounting. said Wheel Q11 the,

support in coaxial relationandneall.each other` to hold the lower. wheelstationary While the otherv is free to revolve, a pinion meshing withboth gear wheels,'power means to carry said pinion bodily andcontinuously around said wheels, a switch mounted 'on the support andhaving two arms arranged one abovethe other and extend-V ing radially ofthe wheels at some distance above the upper wheel, two, ca -n1 devicescomposed of insulating material positioned one on top of the other, onand coaxial'with'Y the upper wheel and havingthereonupwardly facingswitchen'.- ngmc )tracksV tol engage with the ef spp ding switcharrnsonc'di/li: geach rjeyo tion ordis upper wnijtne lowers f j 'device havingat the bottoma'n annular 'aange which at au times underlies the switcharms and prevents them from engaging the latter wheel, a one-way clutchbetween the upper wheel and the lower cam device, means frictionallyholding the cam devices against relative rotary movements, and a. fingerpiece on the upper cam device to shift it angularly of the lower one.

2. A timer mechanism including a support, a stationary tubular postrising from the support, a shaft rotatably mounted in and projecting upfrom the post, two gear wheels surrounding the post in coaxial relationto each other, the lower wheel being xed to the post and the upper wheelbeing rota-table, one of the wheels containing slightly more teeth thanthe other, the upper wheel having a hub on the upper side, a pinionmeshing with both wheels, power means to carry said pinion bodily andcontinuously around said wheels, a switch on said support beside thewheels, a switch actuating cam on, and rotatable with, the shaft justabove the upper wheel and having thereon upwardly facing switch engagingcam tracks, said cam having in the under side a central cavity largerthan said hub, a torsion spring in said cavity around the hub andanchored at one end to the cam to form a oneway clutch between the camand the upper wheel, and a member on the upper end of the shaft forturning the shaft manually, in the direction permitted by the clutch, toshift the cam angularly relatively to the upper wheel.

B. A timer mechanism including a support, a stationary tubular postrising from the support, a shaft rotatable in and projecting up from thepost, detachable key elements on the shaft above and below the post tohold the shaft in place, two gear wheels surrounding the post in coaxialrelation to each other, the lower wheel being fixed to the post and theupper wheel being rotata- 6 ble, onefwoiA the ,wheels` ontainingslightly more een ih, ni. che "ther, the'. fumerKV wheerhvinea han, yon;merca side', pinion meshing winisotu" wheels, poyv mearsA toY carry saidpirfi'iorlhodil'yV`V and continuously' around said wheelsfaswitchon ortbesidejthe iifhe'e'ls,y a switcliactuat' on, ane4 rotatable with, mestair;andyhaving 'a enclosing said hub, said cam 'hav-1 ingu thereonupwardly facing cam"'tracks", and' meansV in he saidcavity"cooperatingfwith the cani andthe hubto form a one-'way clutch beepost, 'one off'lfth'e two uppergearwheelscontai 4' a slightlygreaternumbejrof t'eth'tha'n'the other, its lernst eter wheel beingfafgf'di ameter than the others,V aVV pinion" rotatably mounted on lthelcnvest ygear wheel and me'shi'rig'l with bothmof th'eothe'r wheels,power I'rearis't drive the lowest gear wheel, a switch op'atingrv lmean;composed of two nieibe'rsfoand ge K wheel and each having 'thereonnan'iipwar'ilyN facingY s); ch engaging cam' Ytrackfa 'oeway clutch be.en thecarnandtheupper'whel, Qi @remembers hating Alrlii'd*dellla-i'movement on the other and provided'withafln ger piece to turn the same,a spring pressing said members together to create frictional resistanceto relative angular movements, a switch on said support beside thewheels having two arms each of which extends into the path of one ofsaid cam members, and a member on the upper end of the shaft for turningthe shaft manually.

5. In a timing mechanism, a self closing switch formed of two springarms arranged one above the other and anchored at corresponding endswhile the other ends are free, the arms tending constantly to contacteach other, each arm having thereon a contact piece, at some distancefrom the free end, to engage with the contact on the other arm, thecenter lines of the portions of the arms from the contact pieces to thefree ends being in the same vertical plane, an upright shaft, rotatablein one direction only,

, beside the switch, two cams, one above the other,

on and rotatable with the shaft; the lower cam having thereon anupwardly facing track that passes underneath the free end of the lowerarm of the switch at a predetermined point in each revolution of theshaft, the track being so shaped that both arms are first stressed andraised while remaining in contact with each other, and are then releasedfrom this cam at a second predetermined point in each revolution of theshaft; the upper cam having thereon an upwardly facing cam track thatpasses under the upper switch arm, after the switch arms have beenraised, this track being so shaped that it holds that arm upindependently of the lower cam track during a portion of each revolutionof the shaft and then releases it; and means to adjust the camsrelatively to each other angularly of the shaft so as to determine therelative times at which the two cams release the corresponding switcharms.

"wan @ne snare just abete mej'pper" 6. In a timer mechanism, a rotatableshaft, a power-driven wheel supported independently of the shaft aroundand in coaxial relation thereto, said wheel having a central hub on theupper side thereof, a cam member in the form of an inverted cup on theWheel and interlocked with the shaft for rotation therewith, with saidhub housed in the cavity in the cam member, the diameter of the cavitybeing greater than that of the hub, a torsion spring surrounding andgripping the hub, one end of the spring being free in space and theother end being anchored to the cam member thereby forming a one-wayclutch between the wheel and the cam member. an upwardly facing camtrack on the exterior of the cup, a second cam member surrounding theshaft above the cup and interlocked with the shaft for limited movementsre1- atively thereto, said second cam member also having an upwardlyfacing cam track, an element on the upper end of the shaft to turn thesame manually in the direction permitted by the clutch, a nger piece onthe second cam member for shifting it, and a switch provided with twoelements one of which extends into operative relation to said cam trackwhile the other extends into the path of the track on the second cammember.

7. In a timer mechanism, a rotatable shaft,

a power-driven wheel supported independently ,j

of the shaft around and in coaxial relation thereto, said wheel having acentral hub on the upper side thereof, a cam member in the form of aninverted cup on the wheel and interlocked with the shaft for rotationtherewith, with said hub housed in the cavity in the cam member, thediameter of the cavity being greater than that of the hub, a torsionspring surrounding and gripping the hub, one end of the spring beingfree in space and the other end being anchored to the cam member andthereby forming a oneway clutch between the wheel and the cam member, anarcuate cam track on the exterior of the cup, a second cam member,provided with an arcuate cam track, surrounding the shaft above the cupand interlocked with the shaft for limited movements relatively thereto,an element on the upper end of the shaft to turn the same manually inthe direction permitted by the clutch, a finger piece on the second cammember for shifting it, and a self-closing switch composed of two springarms arranged one above the other, anchor means iixedly supportingcorresponding ends of the arms While the other ends stand free, saidarms extending radially into the paths of the corresponding cam tracks.

DAVID MORRISON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

